Stringed acoustic instruments typically include a pin-in-hole configuration for securing a ball end of the string to a bridge. An example stringed acoustic instrument, a guitar 2, is shown in FIG. 1A. FIG. 1B is a schematic diagram of the pin-in-hole securing design shown in FIG. 1A.
As shown in FIG. 1B, a non-ball end of the string 10 is fed up through a bridge hole until the ball end 14 of the string comes in contact with the underside of the bridge 12. A pin 16 is then inserted into the bridge hole and forms an interference fit with the hole, keeping the string 10 in place. The opposite end of the string, the non-ball end, is then fed over the saddle 18 and secured to a headstock of the instrument. String tension is adjusted using a key on the headstock of the guitar.
The sizes of the holes in stringed acoustic instruments are non-uniform. Additionally, different shapes and sizes of pins are used to form an interference fit with the hole and secure the ball end of the string. In a typical acoustic stringed instrument, string tension can only be adjusted using the keys.